The Department of Meteorology of Freiburg University is running a micrometeorological site in a pine forest in the Rhine valley plane on the south-western edge of Germany. The general purpose of this research station is to carry out investigations on the radiation balance, the energy balance and the water balance of the forest ecosystem there. The station is also a tool for the comparison of methods and the development and validation of models.

2. THE DATA

We now have an almost unbroken time series of measured micrometeorological parameters starting in 1974. In this paper some data sets of temperature measurements within and above the forest stand and on the forest floor are analysed. During the period of observation, which is still going on, the stand heigth more than tripled and the forest management carried out three thinnings, both of which influenced the development of the canopy. Annual and monthly patterns as well as vectors of the whole time series (1974 - 2001) are compared and analysed. It deals with soil temperature, screen temperature, psychrometric measured air temperature below, within and above the forest canopy and the equivalent blackbody radiative temperature of this canopy.

3. THE RESULTS

First, we characterise the influence of forest growth and of changes in its geometry. Second, using comparison with climatological sites of the German Weather Service in the vicinity we define the influence of weather and the possible changes of climate.

4. REFERENCES

Ahrens, D., M.G. Iziomon, A. Matzarakis and H. Mayer, 2001: Impacts of the solar eclipse of 11 August 1999 on routinely recorded meteorological and air quality data in south-west Germany. Meteorol. Z. 10, 215 - 223. Jaeger, L., H.-J. Garthe and A. Kessler, 1986: The climatological site Hartheim: its philosophy, design and special measuring results. Freiburger Geogr. Hefte, 26, 189 - 199. Jaeger, L. and A. Kessler, 1997: Twenty years of heat and water balance climatology at the Hartheim pine forest, Germany. Agr. Forest Meteorology, 84, 25 - 36. Königer, P., S. Uhlenbrook, Ch. Leibundgut L. Jaeger and H. Mayer, 2001: Isotope hydrological investigation on groundwater origin in the flood plain of the Upper Rhine valley. In: Seiler, K.-P. and S. Wohnlich, New Approaches Characterising Groundwater Flow. Lisse, Swets and Zeitlinger, 363 - 366. Mayer, H., L. Jaeger, A. Matzarakis, G. Fernbach and D. Redepenning, 2000: Forstmeteorologische Messstelle Hartheim des Meteorologischen Institutes der Universität Freiburg. Ber. Meteorol. Inst. Univ. Freiburg, 5, 55 - 83.

--------------------------- Corresponding author address: Lutz W. Jaeger, Meteorologisches Institut der Universität Freiburg, Werderring 10, D-79098 Freiburg, Germany; e-mail: jaeger@mif.uni-freiburg.de